Do I need new variator rollers?

[timk225]

My Jonway YY250T (244cc engine) runs good, but it tends to shudder when taking off from a stop. Once it is up to speed it is smooth.

The scooter had 2650 miles when I started riding it a few months ago, and it is up to 4400 miles now. The shudder problem at low speed has always been there.

I was wondering if the variator rollers in this thing might be worn and have flat spots and in need of replacement. Are they round or tapered rollers / sliders, and what is the stock weight?

As for changing the weight of the weights, I would like better mpg, but better bottom end to haul my 275 pound ass up to speed would not be a bad idea either. And from what I read, one thing needs lighter weights and one needs heavier weights.

[wile]

I believe your problem is your CLUTCH, it is slipping at low RPMS. So check your clutch and most likely the PADS are pretty glazed up trying to move the scoot plus your 275 ass(HAHA).
You can get some sandpaper and take off the glaze and it will stop the shuttering at low rpms. The other thing is at what RPMS does it start to shutter JUST when takeing off and then they grab? If they are grabbing at just a little over 2000 rpms the SPRINGS on the Pads might be to weak and are throwing out the Pads to SOON with not enough RPMS to grab the bell good. Springs are cheap and with either 1000 or the OEM springs the clutch will work better the OEMs are rated at around 700-800. That will require little higher RPMs to throw out the PADS but it will have enough rpms to keep hold of the Bell.
Wile

[chromestarhustler]

i gotta agree with mr wile here, glazed clutch, probably sand it and be good. i usually get about 3-5k between service jobs its a heavy scooter and i hammer the gas..

[wile]

DAMN, Just got a PROMO now I am MR WILE instead of HEY YOU(HAHA).

[timk225]

I'm not sure which part of the clutch is what you are referring to. Diagrams? Is the clutch the entire variator assembly that is on the engines' crankshaft?

Any instructions or videos on how to take it apart and inspect it?

[fairweasel2323]

scooterdoc.proboards.com/index.cgi?board=transmission&action=display&thread=1378
This might help u the clutch is in the rear by tire the variator in front by motor. U should take ur clutch bell housing off to access the pads and springs my shuddering I fixed without removing the bell housing just little wd40 on springs but will slip for a little then shuddering gone but would not recommend my bell housing is already purpled and warped so its getting replaced or I would have removed it to Sand the pads

[onilegion]

Hi timk225,

Before you try taking off the clutch, give this a try. Using a good, preferably oilless compressor and blowgun, dust the heck out of every nook and cranny on the clutch and on the interior surfaces of the CVT ( you will only need to remove the CVT cover to do this). Then take it out a give it a try.

The black dust that you will find in the CVT, is rubber dust from wearing of the belt. When it gets built up on the friction surfaces of the clutch it can cause grabbing and shuddering when the clutch engages. If the build-up has gotten too thick, or has been present for a long time, then you will have to service your clutch as others have outlined above.

Hope this helps,
onilegion <><

[skuttadawg]

How much throttle do you give it on takeoff ? Too little and it may be not engaging like it should and be slipping in the bell which causes glaze up . Try giving it more throttle and see how it works .

Rollers weights wear out just like all mechanical parts . The are round cylinder shaped and will get flat spots which prevent them from rolling as good and make a rattle sound . At 5,5500 miles the rollers in my Echarm were just starting the develop flat spots but still mostly round . I replaced with DrP sliders and love how much better they are . First they last longer , do not make annoying rattle sounds ( I though tit was a bad crank bearing on my older 50 at first ) , acceleration was a more steady curve , and I gained 5 mph on top end . I had 12.2 g and went with 12g sliders . Well takeoff was a hairless but I am happy . I want totry lighter ones to have a faster takeoff as above 60 mph its sketchy anyways and at 75 mph its stunt driving .

Remove the CVt cover to inspect the belt as they wear out and will need replacing at some time . If there is any black rubber dust from the belt wear clean it out .

When it comes to tuning its like a see saw . More speed on takeoff = less mpg just as more mpg = less takeoff speeds . When you add or take away from one side it effects the other . CVT tuning will take some trial and error to get it as desired . Lighter variator weights help on take off and up hill but too light lessen the top end . You may want to upgrade the clutch and contra springs to higher rpm rated ones that engage at a higher rpm so it will have more power when engaged at first . They come in 1,000 , 1,500 and 2,000 which means they rated speed is that much more than stock ones to engage the clutch . Stock exhaust has a catalytic convertor in it and an unrestricted most of the time does not so exhaust flows out better . A K&N or Uni air filter can improve the air flowing into the engine . Both will require a larger main jet in the carb to avoid being lean .

Clean the airfilter and spray some carb cleaner in the carb . You can do this without removing the carb . For dirty jets however you will need to remove the carb and remove the bowl on the bottom to remove the jets for a more thorough cleaning . Put in a NGK iridium sparkplug will help it run at its best .

You can a get a BBK ( big bore kit which is a larger piston ) with more power it can move you easier and not have to work as hard and save on fuel . However with a BBK if you ride at WOT it will drink more gas . I had a Silverado 2500 4x4 with a 454 engine in it . I got better mpg than two of my friends that had a 1500 series with a 350 engine . The 454 has so much torque it takes little effort to move it and I could go 35 mpg idling once in high gear with an AT . If I floored it the gas gauge went down as the speedo went up . So there is a balance of mpg and power .

To truly get better mpg AND speed an EFI kit is the way to go . With EFI fuel is pressurized by an electric pump and sprayed into the engine rather than drawn in by vacuum so its more efficient . My Echarm is my first EFI two wheeler and wow it has the power . I rode several GY6s with a carb and let my friends with one ride my Echarm . Everyone agreed EFI was almost like having a turbo since it never stalls or bogs and throttle response is instant Here is some kits to look at ecotrons.com/index.php?ncr=1

A HP clutch can have better friction material on the shoes and a thicker amount along with a better bell too . Dr Pulley clutches come with several springs sets and weights so you can truly tune it better . A larger diameter variator can have more top end but less on take off .

Replace the China tires with Pirelli , Avon or Michelin which will ride , brake , handle , better wet traction , higher speed rating and weight load bearing . Get the tires balanced really smooths out the ride and may help mpg since it has less vibration as most are not balanced .

I heard some have gained top end with a windshield . Research it as they shape can help or hurt if more air drag .

You can always find a scooter buddy with a 49cc scooter so you will always be faster than him lol

[wile]

Here are the pads, and with the miles you have on it and never have gone into the CVT I am sure they are pretty well glazed up(in other words they will be shiny and smooth and not rough). They should be like Coarse Sandpaper.
Wile

[chromestarhustler]

be careful taking advice from just anyone, read, study and learn who knows their stuff. figure out who does things like you do. I would never recommend avons unless its track day and your gonna be knee sliding (haha knee sliding this big heavy 250 scooter), OTHERWISE too damn soft they wear quickly, there are 2 threads about it and tires just this week, michelin ok, pirelli more price for no more performance, kenda and shinkos equal or out perform most other scooter tires for less.

since your probably noticing it about now, rears wear faster, way faster on these heavy 250 scooters, you will replace rears 2 or three times before the front. luckily good kendas or shinkos are under 40 bucks

a bbk and efi isnt required, both are expensive for these engines. i am on my second or third twin of your scoot, except i have the 257. i was up to 80mph on the highway today with throttle and rpm left and mine is actually set up more for city drivng, where i do 99 percent of my riding so its set up more for getting to 50ish ahead of cars and weaving out of traffic.

givis tall windshield does not make this sucker faster, its a big damn square at a slight angle i do not think the airflow version is out yet. i do recommond the aftermarket reflex seat its mucho comfy.

[timk225]

I took the CVT cover off today, and I cleaned it up good with Simple Green, hot water, and paper towels. I also sprayed Simple Green all in and around the rear plate of the belt area and hot water rinsed it out too.

Then while I was at it, I changed the gear oil in the rear end, I had some Valvoline 80w-90 gear oil left over from another job a few months ago so it finally got used.

The clutch bell had no heat discoloration at all on it, so that's a good sign. I need to go to a friends' house to take the bell off, he has an air impact wrench to break that nut loose with.

[nulldevice]

I had been rather concerned about over tightening the variator and clutch nuts with my impact wrench.

What I now do is tighten the nut finger tight.
Next I make a mark on the face of the nut in line with a line on the clutch bell or variator fan face.
I then use the impact wrench and check to see If the nut has tightened 1/4 to 1/3 turn.

[hanilanzi]

yep, null, same here, i got an impact wrench tool where i can control the impact power, and i set it on half instead on all the way and seems like it turns it about another 1/3 turn after finger tight.
wouldn't want to see that nut brake on me

[marvinlee]

OMG!!!! This information is exactly what I have been looking for; vidios and all. Sweet! See I just bought a 250cc lance duke with about 1409 kilometers on it. I have a slight vibration upon take off then smooth as silk. Thanks you guys for all of the diagrams and all. Marvin.